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INTRODUCTION
A structural member, carrying an axial compressive load is called a strut. But a vertical strut used in building is called a column.
• A column is a compression member having an
effective length greater than 3times the least lateral
dimension.
• When the ratio of effective length of the column to
its least lateral dimension does not exceed 15, thecolumn is termed short column, otherwise long or
slender column.
BS8110 Part II (1997) Requirements
• The area of longitudinal reinforcement in a column should not be les than 0.8% of the area of concrete section required for direct load alone and it should not be more than 3% of gross cross-sectional area of the column.
• The diameter of the longitudinal bars should not be less than 12mm. The cover should not be less than 40mm.
• A reinforced concrete column having helical reinforcement, should have at least six bars of longitudinal reinforcement.
• The effective lateral support to a column is provided by transverse reinforcement. The pitch of the transverse reinforcement should not be more than the minimum value of the following:
• Least lateral dimension of the column.
• Sixteen times the diameter of the longitudinal reinforcing bar nearest to the compression face of the member.
• Forty eight times the diameter of the transverse reinforcement.
COLUMN CLASSIFICATIONS AND PROPERTIES
Braced and Unbrace
Design Information:
The following are assumed design/materials information:
• Material stresses and unit loads:
concrete stress, fcu = 25N/mm^2
steel stress, fy = 410N/mm^2
live load, = 2.0kN/m^2
partition allowance = 1.0kN/m^2
finishes = 1.2kN/m^2
roof load, dead and live = 1.5kN/m^2
wall load and finishes = 3.47kN/m^2
• Member sizes:
floor beam size: 450 x 225mm
roof beam size: 225 x 225mm
column size: 225 x 450mm
REFERENCE
Martina Schnellenbach-Held, StefanEhmann, Karsten Pfeffer:
“BubbleDeck - New Ways in Concrete Building”. Technische
Universität Darmstadt, DACON Volume 13, 1998
Martina Schnellenbach-Held, Karsten Pfeffer: “BubbleDeck Design of
Biaxial Hollow Slabs”. Technische Universität Darmstadt, DACON Volume 14, 1999
BubbleDeck Report from A+U Research Institute /Professor Kleinmann
- the Eindhoven University of Technology / the Netherlands, 1999
BubbleDeck Test Report by Koning & Bienfait b.v. / The
Netherlands, 1998
U.S. Department of the Army (1999). Concrete, Masonry and
Brickwork. General Publishing Company. pp. 158–160.
American Concrete Institute, Building Code Requirements for
Structural Concrete (ACI 318-08) and Commentary. Ach is the
cross-sectional area of a structural member measured to the outside edges of
transverse reinforcement. ACI 318-08 pg 19
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